1. Field
The described technology relates generally to an organic light emitting diode (OLED) display.
2. Description of the Related Technology
An organic light emitting diode (OLED) includes two electrodes and an organic emission layer. The organic emission layer is disposed between the two electrodes. Electrons injected from one electrode and holes injected from the other electrode are combined in the organic emission layer. As such, excitons are formed and light is emitted by energy generated from the excitons.
An organic light emitting diode (OLED) display includes a plurality of pixels, each pixel having at least one organic light emitting diode (OLED) of a self-light emitting element. Each pixel further includes a plurality of transistors and a plurality of capacitors to drive the organic light emitting diode (OLED). The plurality of transistors include a switching transistor and a driving transistor.
A driving transistor flows a current of one magnitude through a driving semiconductor layer. As such, a compensation transistor for compensating a threshold voltage and a light emission control transistor for controlling light emitting may provide another current of the same magnitude. In order to quickly compensate the threshold voltage of the driving transistor when a length of the driving semiconductor layer of the driving transistor is short, an s-factor of a transistor characteristic curve decreases and a change rate of the current increases according to a change of the voltage applied to the driving gate electrode. As such, a large current is provided to the organic light emitting diode (OLED). However, this may cause spots. In contrast, when the length of the driving semiconductor layer of the driving transistor is long enough to prevent the spots, the threshold voltage of the driving transistor is slowly compensated by a small current such that low grayscale compensation is not obtained and the spots are generated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it disclosed technology contains information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.